Book excerpt: A theoretical and empirical contribution to the quest for sustainability and environmental quality. The book examines the physical and economic aspects of flows of materials and products, as well as the policies and strategies designed to reduce the related resource depletion and environmental pollution. The `material-product chain' concept forms a general framework, defined as a system of linked flows of materials and products that support the provision of a certain service. Various economic models of material-product chains are studied, both theoretical and applied, such as static optimisation, dynamic simulation and general equilibrium models. Applications to metals, rain gutters and window frames are described. Audience: Readers in universities, research organizations and policy institutes interested in the environment, economics and government policy.